Background: Urinary tract infection (UTI) is a common clinical problem during pregnancy that can have serious consequences for the mother and fetus. Some studies have suggested that UTI can trigger or aggravate preeclampsia. The present study aimed to investigate the association between urinary tract infection in the first trimester and the risk of preeclampsia in pregnant women referring to Bahar hospital of Shahroud. Patients and Methods: In this case-control study, 92 pregnant women with a diagnosis of preeclampsia were selected as cases, and for comparison 92 pregnant women were selected as control. History of previous UTI in the first trimester was assessed as a risk factor. Data were analyzed using SPSS 16 software and related statistical tests such as mean and standard deviation, chi-square, and independent t-test. Results: In this study, the mean age of the patients was 28.6 ± 6.9 years that no significant differences were found between the two groups. It was also found that 37 (40.2%) patients in the case group and 29 (31.5%) patients in the control group had a UTI which was significantly (p<0.043) higher in the case group. Also, in the multivariate regression model, UTI was significantly associated with preeclampsia (p<0.048), so that UTI increases the risk of preeclampsia (OR=1.86). Conclusion: The results of this study showed UTI during the first trimester of pregnancy is associated with the risk of preeclampsia. Therefore, controlling and treatment of urinary infections can reduce the risk of preeclampsia in the later months.